The use of enzymes derived from microbial cells to effect specific chemical transformations is well known. In carrying out such transformations, the cell-free enzyme preparation, ruptured cells or whole cells can be used as the source of biocatalyst. The free enzyme or cell can be efficiently used in batch-type processes but do not lend themselves to continuous industrial scale processes. This difficulty has led to increased interest in the preparation of various forms of immobilized enzymes.
U.S. Pat. No. 3,779,869 (issued Dec. 18, 1973) discloses the stabilization of glucose isomerase activity by treating whole bacterial cells with glutaraldehyde. The use of gluaraldehyde for the immobilization of ruptured cells to provide a coherent solid product having glucose isomerase activity is disclosed in U.S. Pat. No. 3,980,521 (issued Sept. 14, 1976).
U.S. Pat. No. 4,060,456 (issued Nov. 29, 1977) involves the stabilization of microbial cell material having glucose isomerase activity by treating it with a cationic, polyelectrolyte flocculating agent such as a polyethyleneimine or polyvinylpyrolidone. The use of polyelectrolytes such as polyamines and cationic, polyacrylamides in the stabilization of microbial cells having active enzymes associated therewith is disclosed in U.S. Pat. No. 3,989,596 (issued Nov. 2, 1976).
Ono et al describe the immobilization of naringinase from Aspergillus niger by adsorbing the enzyme to tanninaminohexyl cellulose prepared by the reaction of aminohexyl cellulose and cyanogen bromide activated chinese gallotannin in Agric. Biol. Chem., 42(10), 1847-1853 (1978).
Ohba et al disclose in Biotechnology and Bioengineering, Vol. XX, Pp. 665-676 (1978) that pullulanase can be successfully immobilized by the addition of tannic acid to the culture filtrate of thermophilic Streptomyces flavochromogenes to form a tannin-pullulanase adduct which can then be bound to TEAE-cellulose.
There is disclosed in U.S. Pat. No. 4,212,943 (issued July 15, 1980) a bacterial cell aggregate having increased particle hardness which is produced by contacting a mass of bacterial cells with a crosslinked reaction product of glutaraldehyde or cyanuric halide and a cationic polymer obtained by polymerization of an epihalohydrin and an alkylenepolyamine.